Magnetoresistive (MR) heads are employed in magnetic data storage systems, such as magnetic disc drives, to read data from the storage media. More particularly, the MR head employs an MR element whose resistance changes with changes in the confronting magnetic field. As the disc rotates adjacent the MR head, changing magnetic fields due to recorded data on the disc moving past the MR element induce changes in the resistance of the MR element. A fixed bias voltage is applied to the MR element to generate a current across the MR element representative of the data. The voltage changes with the resistance to provide signals representing the data.
Often, the bias voltage is chosen to be a maximum allowable for the particular MR head design, or for other supporting components. Using a maximum bias voltage increases the signal swing in the resulting sensed current in the presence of changing magnetic fields. However, using a maximum bias voltage with the MR head stresses the head and potentially decreases the head's life span and/or increases potential head instability issues at reliability stages.
Embodiments of the present invention offer advantages which can be useful in data storage systems which provide a bias current or voltage to an MR head.